Towards a "crippled-mode" operation of an industrial wastewater treatment plant

In house treatment of metal plating wastewater mainly involves chemical treatments performed in continuous flow stirred tank reactors (CFSTR). The inflow of these tanks is directly produced by the plating shops activity, and the storage capacity never exceeds a few hours of incoming flow. Thus, any fault on one of the CFSTR may impose a complete stop of the whole manufacturing process, which is unacceptable for the manufacturer. Another solution would be having "spare" CFSTRs ready to be used as alternative in case of any CFSTR fault or maintenance. The latter solution however implies additional costs in equipment, storage space and maintenance so as to keep this equipment fit and ready for operation. The paper presents the study of a "crippled-mode" wastewater treatment (WWT) operation which enables a sufficiently efficient working of the WWT plant during maintenance phases and failure repairing on any of the CFSTR, without any extra equipment needed. This survey has been performed on real industrial WWT plants, with a continuous influent and under industrial operation constraints. The performances of the detoxication have been analysed when a CFSTR is short-circuited and the corresponding chemical treatment is shunt in the upstream or downstream CSFTR. This work shows the possibility of satisfying the environmental regulations with a WWT plant functioning under subnormal conditions.     

Electricity assisted anaerobic treatment of salinity wastewater and its effects on microbial communities

High salinity wastewater is often difficult to treat using common anaerobic technologies. Considering that high conductivity of salinity wastewater may enhance electrodes reaction to accelerate the decomposition of volatile fatty acids produced in anaerobic digestion, a pair of electrodes was packed into an anaerobic reactor (R1) with the aim to enhance the treatment of salinity wastewater. With increasing the salt concentration (NaCl) gradually from 0 to 50 g/L in 137 days' operation, COD removal in this reactor under the voltage for the electrodes of 1.2 V was well maintained at 93%, while the COD removal in a reference anaerobic reactor without electrodes (R2) decreased to 53%. When the voltage for R1 was cut off, about 10% COD removal was declined, which was still 30 percentage points higher than that in R2. The electrodes enhanced the biodegradation of volatile fatty acids, especially propionate. Fluorescence in situ hybridization analysis confirmed that the relative abundance of propionate-utilizing bacteria in R1 was significantly higher than that in R2. PCR-DGGE analysis of bacteria and archaea domains indicated that the electric field stimulation effectively enriched salt-adapted microorganisms during the treatment.     

华南地区某污水处理厂工程设计

针对华南地区某污水处理厂污水处理的特点和难点,探讨了该厂污水处理工艺设计,介绍了AAO污水处理工艺流程,并阐述了各主要构筑物工程设计及相关参数,为今后类似污水处理厂项目设计积累了一定经验。     

Influence of pharmaceutical residues on the structure of activated sludge bacterial communities in wastewater treatment bioreactors

Concern is growing over contamination of the environment with pharmaceuticals because of their widespread use and incomplete removal during wastewater treatment, where microorganisms drive the key processes. The influence of pharmaceuticals on bacterial community structure in activated sludge was assessed in small-scale wastewater treatment bioreactors containing different concentrations (5, 50, 200 and 500 μg L⁻¹) of several commonly used pharmaceuticals (ibuprofen, naproxen, ketoprofen, diclofenac and clofibric acid). T-RFLP analyses of the bacterial 16S rRNA genes indicated a minor but consistent shift in the bacterial community structure in the bioreactor R50 supplied with pharmaceuticals at a concentration of 50 μg L⁻¹, compared to the control reactor R0, which was operated without addition of pharmaceuticals. In the reactors operated with higher concentrations of pharmaceuticals, a greater structural divergence was observed. Bacterial community composition was further investigated by preparation of two clone libraries of bacterial 16S rRNA genes from reactors R0 and R50. Most clones in both libraries belonged to the Betaproteobacteria, among which Thauera, Sphaerotilus, Ideonella and Acidovorax-related spp. dominated. Nitrite-oxidizing bacteria of the genus Nitrospira sp., which are key organisms for the second stage of nitrification in wastewater treatment plants, were found only in the clone library of the reactor without pharmaceuticals. In addition, diversity indices were calculated for the two clone libraries, indicating a reduced diversity of activated sludge bacterial community in the reactor supplied with 50 μg L⁻¹ of each of selected pharmaceuticals.     

Simultaneous removal of carbon and nutrients from an industrial estate wastewater in a single up-flow aerobic/anoxic sludge bed (UAASB) bioreactor

Simultaneous removal of carbon and nutrients (CNP) in a single bioreactor is highly significant for energy consumption and control of reactor volume. Basically, nutrients removal is dependant to the ratio of biochemical oxygen demand to chemical oxygen demand (BOD₅/COD). Thus, in this study the treatment of an industrial estate wastewater with low BOD₅/COD ratio in an up-flow aerobic/anoxic sludge bed (UAASB) bioreactor, with an intermittent regime in aeration and discharge, was investigated. Hydraulic retention time (HRT) of 12-36 h and aeration time of 40-60 min/h were selected as the operating variables to analyze, optimize and model the process. In order to analyze the process, 13 dependent parameters as the process responses were studied. From the results, it was found, increasing HRT decreases the CNP removal efficiencies. However, by increasing the BOD₅ fraction of the feed, the total COD (TCOD), slowly biodegradable COD (sbCOD), readily biodegradable COD (rbCOD), total nitrogen (TN), and total phosphorus (TP) removal efficiencies were remarkably increased. Population of heterotrophic, nitrifying and denitrifying bacteria showed good agreement with the results obtained for TCOD and TN removal. The optimum conditions were determined as 12-15 h and 40-60 min/h for HRT and aeration time respectively.     

ICEAS工艺启动及活性污泥培养驯化应用实例

结合福州市金山污水处理厂工艺及及活性污泥培养驯化实例,分析总结ICEAS工艺启动及活性污泥培养驯化经验。     

谈大中城市小型污水厂的建设

以济南市小型污水处理厂的建设规划为背景,介绍了近期拟建污水处理厂的情况,分析了目前污水处理存在的问题,提出了应将污水处理和节水相结合的思路,从而提高城市污水处理率和中水回用率,节约水资源。     

Analysis of the bacterial community in a laboratory-scale nitrification reactor and a wastewater treatment plant by 454-pyrosequencing

For full understanding of the microbial community in the wastewater treatment bioreactors, one of the feasible and effective ways is to investigate the massive genetic information contained in the activated sludge. In this study, high-throughput pyrosequencing was applied to analyze the 16S rRNA gene of bacteria in a laboratory-scale nitrification reactor and a full-scale wastewater treatment plant. In total, 27,458 and 26,906 effective sequence reads of the 16S rRNA gene were obtained from the Reactor and the wastewater treatment plant activated sludge samples respectively. The taxonomic complexities in the two samples were compared at phylum and genus levels. According to the pyrosequencing results, even for a laboratory-scale reactor as simple as that in this study, a small size clone library is far from enough to reflect the whole profile of the bacterial community. In addition, it was found that the commonly used informatics tool “RDP classifier” may drastically assign Nitrosomonas sequences into a wrong taxonomic unit resulting in underestimation of ammonia-oxidizing bacteria in the bioreactors. In this paper the reasons for this mistakenly assignment were analyzed and correction methods were proposed.     

Energy consumption in an urban wastewater treatment plant: the case of Murcia Region (Spain)

Of all the costs associated with the operation and maintenance of wastewater treatment plants (WWTPs), those associated with energy use tend to be the most significant. From this point of view, it is hence logical that energy efficiency and saving strategies should be one of the current focuses of debate amongst those involved with the management of WWTPs. The present study's objective is to determine the correlation between size and energy consumption for a WWTP. To this end, 90 WWTPs currently in service were analysed and their energetic impact quantified in terms of kWh/m³ of water treated. The results obtained demonstrate that energy consumption ratio increases as the size of WWTPs decreases, either in terms of treatment volume or population equivalent served.     

污水处理厂恶臭防治对策及环境影响评价的研究

城市污水处理厂的恶臭严重影响了污水处理厂周围居民的日常生活,通过对城市污水处理厂的恶臭来源和国内外污水处理厂恶臭防治措施的现状分析,重点从环评角度对污水处理厂恶臭的环境影响评价方法进行了研究,从实测、嗅闻调查以及大气防护距离的确定三个角度进行综合全面的评价分析.     

Determination of virus abundance, diversity and distribution in a municipal wastewater treatment plant

Procedures to extract and count sludge viruses-like particles from municipal sewage treatment plant were optimized by epifluorescence microscopy using SYBR Green I as a stain. The highest indigenous virus yields from the bulk of the anaerobic digestion sludge and influent (solid) were obtained by utilizing 10 mM sodium pyrophosphate as eluant solution with vortex and 1 min of sonication. The use of 1× phosphate buffered saline as eluant with vortex and 1 min of sonication yields highest indigenous virus from activated sludge. The efficiency of extracting indigenous viruses by sodium pyrophosphate-ultrasound treatment was about 62% of the extractable virus particles from activated sludge and 87% for anaerobic digestion sludge, respectively. Samples treated with DNase had decreased, but not significant, virus counts, suggesting a minor effect of extracellular DNA on virus count. Following the optimized procedure, we investigated the abundance and diversity of virus particles in the wastewater stream of a municipal treatment plant. The concentrations of virus particles ranged from 0.28 × 10⁹ ml⁻¹ to 27.04 × 10⁹ ml⁻¹. Transmission electron microscopy (TEM) showed a high variety of virus morphotypes in sludge. Pulsed-field gel electrophoresis (PFGE) revealed a diverse and dynamic viral community in different stages of the system with genome sizes ranging from 33 kb to >350 kb with most of the viral DNA in the 30-80 kb and 200-350 kb size ranges. Collectively, our study suggested that indigenous viruses are abundant and dynamic in the municipal wastewater treatment system and may play an important role in functioning of the system.     

纺织污水处理厂厌氧水解及接触氧化工艺调试

介绍了空港经济区纺织污水处理厂＂厌氧水解＋接触氧化＋化学混凝法＋沉淀分离＂组合工艺的运行调试过程,针对纺织废水水质间歇性超标、水质波动大以及纺织废水与市政污水的比例波动等问题,通过合理调整气水比、溶解氧、生物膜厚度、加药量等工艺参数,使系统的出水水质达到了设计要求,可为同行业污水处理厂的试运行调试提供参考。     

三峡库区城镇污水厂污泥土地利用可行性研究

针对三峡库区城镇污水厂污泥处理处置现状,分析了三峡库区城镇污水厂污泥特性和库区土壤特性,提出在三峡库区开展污泥的土地利用是一种适宜的资源化利用方式。     

Effect of cow slurry amendment on atrazine dissipation and bacterial community structure in an agricultural Andisol

Atrazine is a commonly used herbicide for maize production in Chile, but it has recently been shown to be ineffective in soils that receive applications of cow slurries generated from the dairy industry. This effect may be caused either by the sorption of the pesticide to organic matter or more rapid degradation in slurry-amended soils. The objectives of this study were to evaluate the effects of cow slurry on atrazine dissipation, the formation of atrazine metabolites and the modification of bacterial community in Andisol. The cow slurry was applied at doses of 100,000-300,000 L ha^− 1. After 4 weeks, atrazine was applied to the slurry-amended soils at concentrations of 1-3 mg kg^− 1. The amounts of atrazine and its metabolites were determined by high performance liquid chromatography (HPLC). The soil microbial community was monitored by measurement of CO₂ evolution and changes in bacterial community using PCR-DGGE of 16S rRNA genes. The results show that cow slurry applications had no effect on atrazine dissipation, which had a half-life of 15-19 days. The atrazine metabolites were detected after 20 days and were significantly higher in soils amended with the slurry at both 20 and 40 days after application of the herbicide. Respiration rates were elevated after 10 days in all soils with atrazine addition. Both the atrazine and slurry amendments altered the bacterial community structures, indicated by the appearance of specific bands in the DGGE gels after 10 days. Cloning and sequencing of the 16S rRNA genes from the DGGE gels showed that the bands represented various genera of β-proteobacteria that appeared in response to atrazine. According to our results, further field studies are required to explain the lower effectiveness of atrazine in weed control. These studies may include the effect of dissolved organic carbon on the atrazine mobility.     

污水处理厂土建阶段施工要点及质量控制分析

通过总结多年施工经验和教训,针对污水处理厂土建阶段施工重点和难点,分析了混凝土构筑物防渗漏、预应力混凝土水池、沉井、异形混凝土构筑物等施工要点和施工过程中的质量控制关键点,提出了相应的管理措施。     

污水厂出水SS偏高问题研究及措施

研究了上海某A/B/C活性污泥工艺污水处理厂出水SS偏高的问题,对影响出水SS的主要影响因素进行了综合分析,并提出了工艺调整措施,在实际运行中取得了较好的效果。     

Treatment of high-strength dairy wastewater in an anaerobic deep reservoir: analysis of the methanogenic fermentation pathway and the rate-limiting step

The wastewater of the largest dairy factory in Israel (Tnuva, Tel-Yosef), discharging approximately 6000 tons BOD per year, is treated in two serial, deep reservoirs (anaerobic/facultative). In this study, which focused on the anaerobic reservoir, we combined in situ measurements (over 18 months) and supporting lab experiments, in order to evaluate its efficiency and to identify the rate-limiting step of the methanogenic fermentation pathway. The anaerobic reservoir could remove above 75% of the BOD and COD all year round, but this was not enough to prevent malodors during the winter. Acetate and propionate, products of lactose fermentation, were the predominant intermediate metabolites in the reservoir and their concentrations were strongly dependent on the temperature and the organic load. The combined effects of colder winter temperatures and seasonal increase of organic load, resulted in a decreased rate of propionate oxidation and a consequent accumulation of soluble BOD and COD. Laboratory batch experiments, conducted during this season, found propionate oxidation to be the rate-limiting step in the process, characterized by a lag period preceding its degradation.     

Sequential modeling of fecal coliform removals in a full-scale activated-sludge wastewater treatment plant using an evolutionary process model induction system

We propose an evolutionary process model induction system that is based on the grammar-based genetic programming to automatically discover multivariate dynamic inference models that are able to predict fecal coliform bacteria removals using common process variables instead of directly measuring fecal coliform bacteria concentration in a full-scale municipal activated-sludge wastewater treatment plant. A sequential modeling paradigm is also proposed to derive multivariate dynamic models of fecal coliform removals in the evolutionary process model induction system. It is composed of two parts, the process estimator and the process predictor. The process estimator acts as an intelligent software sensor to achieve a good estimation of fecal coliform bacteria concentration in the influent. Then the process predictor yields sequential prediction of the effluent fecal coliform bacteria concentration based on the estimated fecal coliform bacteria concentration in the influent from the process estimator with other process variables. The results show that the evolutionary process model induction system with a sequential modeling paradigm has successfully evolved multivariate dynamic models of fecal coliform removals in the form of explicit mathematical formulas with high levels of accuracy and good generalization. The evolutionary process model induction system with sequential modeling paradigm proposed here provides a good alternative to develop cost-effective dynamic process models for a full-scale wastewater treatment plant and is readily applicable to a variety of other complex treatment processes.     

Seasonal tertiary wastewater treatment in California: an analysis of public health benefits and costs

A number of communities in the Central Valley of California have requested that seasonally based effluent limits be developed for their wastewater treatment facilities. These seasonal limits would be based on disinfected secondary treatment during the winter and disinfected tertiary treatment during the rest of the year. Such a request for seasonal limits raises a significant water quality policy question with regard to the costs and relative benefits of tertiary treatment during the winter season. A benefit-cost analysis for winter season tertiary wastewater treatment in California's Central Valley is presented here. The assumed societal benefit of winter tertiary treatment is enhanced water quality for recreational purposes, and thus reduced risk to public health. Based on the results of this analysis, between four and sixteen million recreation events would need to occur annually region-wide during the winter to justify the costs of winter tertiary treatment. A similar method and the information described herein could be used by the state water quality regulatory agency to develop a risk-based policy to consider seasonal limits.     

Characterization of biofilm structure and its effect on membrane permeability in MBR for dye wastewater treatment

Two membrane bioreactors were operated at aerobic (DO=6.0mg/L) and anoxic (DO<0.3mg/L) conditions for the treatment of synthetic dye wastewater to determine the effect of dissolved oxygen on membrane filterability. The rate of membrane fouling for the anoxic MBR was five times faster than that for the aerobic MBR. Differences in the nature of the biofilm that was formed on the membrane surface as the result of different DO level was the main factor in the different fouling rates. The biofilm structure was characterized using digital image analysis techniques. Biofilm images were obtained using confocal laser scanning microscopy (CLSM) at various operation points. Structural parameters were then computed from these images using an image analysis software (ISA-2). The structural parameters indicated that the anoxic biofilm was thinner than the aerobic biofilm but the anoxic biofilm was spread out on the membrane surface more uniformly and densely, resulting in the higher membrane fouling. Based on the extracellular polymeric substances (EPS) visualization and quantification, it was also found that EPS, key membrane foulants were spread out more uniformly in the anoxic biofilm in spite of lower amount of EPS compared to that in the aerobic biofilm.